The study considered what would happen if people kept emitting more greenhouse gases until about 2050 and then started cutting emissions.

"Some refer to this as a middle-of-the-road scenario" for tackling greenhouse gas emissions, said study co-author Thomas Knutson, a research meteorologist with the U.S. National Oceanic and Atmospheric Administration (NOAA).

In this scenario the world became about 4.5 degrees Fahrenheit (2.5 degrees Celsius) warmer than today.

In turn, the western Atlantic Ocean—north of the Caribbean Sea up to the Carolinas—saw a doubling of category 4 and 5 storms, the most powerful kinds, by 2100. Today the Atlantic suffers an average of 14 of these intense hurricanes per decade.

Category 4 storms have sustained wind speeds of 131 to 155 miles (211 to 249 kilometers) an hour. Category 5 hurricanes have winds exceeding 155 miles (249 kilometers) an hour.

"I was quite surprised," said Morris Bender, also a NOAA research meteorologist and the lead author of the new study, to be published tomorrow in the journal Science.

"I didn't expect a doubling. I didn't expect we'd see this much response."

Kevin Trenberth of the National Center for Atmospheric Research, in Boulder, Colorado, said there's still a lot of room for improvement in how all of today's climate simulations represent hurricanes and the oceans.

Even so, the new study does bolster an emerging consensus on how climate change will affect hurricanes, added Trenberth, who also was not involved in the research.

"The best information we have now supports the view that tropical storms will likely decrease in number," he said. "But the risk of category 4 and 5 storms could increase."